Question

a bus covers a distance of 250km from delhi to Jaipur towards west in 5hrs. in the morning and returns to delhi in the evening covering the same distance of 250km in the same time of 5hrs.
find average speed
average velocity of the bus for the whole journey

Answer 1

avg speed = (speed1+speed2)/2

speed1= 250/5
          =  50 m/s
speed2= 250/5
          = 50m/s

avg speed=( 50+50)/2
               = 50 m/s

avg velocity =0 because the displacement is 0 as the bus came back to Delhi covering the same distance  

Answer 2

Answer:

To calculate average speed of the bus we will calculate speed of the bus from Delhi to Jaipur and then again from Jaipur to Delhi and find its average. Average velocity of the bus will be Zero

Explanation:

Journey from Delhi to Jaipur

Distance travelled by bus from Delhi to Jaipur = 250 km

Time taken = 5 h

Speed = Distance/ Time

Let Speed 1 be the speed of bus from Delhi to Jaipur

so, here Speed1 = 250/5

                           =50 km/h

Journey from Jaipur to Delhi

Let Speed2 be speed from Jaipur to Delhi

Now here Speed2 = 250/5

                               = 50 km/h

Average speed = Speed1+ Speed2 /2

                           = 50 + 50 / 2

                           = 50 km/h

Average speed is a scalar quantity so it is independent of direction.

Velocity is a vector quantity, i.e. it is dependent of direction.

Velocity of bus  = Displacement/time

The total displacement of the bus is zero as it has finally returned to its original position. Therefore velocity of the bus will also be zero.

Velocity of bus = 0/ 5

                         = 0

As a result average velocity of bus will also be 0.